Ground loop isolator? | Ford Explorer Forums - Serious Explorations

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Ground loop isolator?


Explorer Addict
October 17, 1999
Reaction score
City, State
Gilbert, AZ
Year, Model & Trim Level
'07 XLT V8
Well.. this is on my Focus, not my Explorer... but figured I would get some sound advice here. I just had a system installed in the focus and we are getting some whine on the speakers that increases during acceleration. The installer tried moving some wiring around and minimized the whine but was unable to remove it. He is suggesting purchasing some ground loop isolators. My question is, does the usuage of the ground loop isolator impact sound quality? I am currently using Rockford Fosgate speakerwite and amp kits to wire the system.

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it'll make it a bit quieter on the speakers so you'll have to turn yr volume up a bit more. did he keep the power lead to the amps as far away from the phono leads and speaker leads as poss?
that will minimise the noise even more


Try grounding the amp(s) to factory grounds...

I had a shop do it cuz ive never installed a system, and didnt want to get that involved...but Ill see If I can figure out how he has it wired up.

BTW, I have 2 amps. Will I notice a whine like that on my subs too?

Use large wire (#10 or larger) and run both Amp grounds to the same point. I second the suggestion to use the factory grounding point if possible.

Anybody happen to know where the factory grounding point is in a 03 Focus sedan?

Also, being that I am running two amps (mounted to a board in the trunk), is it likely that I am picking up noise on the RCA's? Would upgrading the wires to something better be the way to go? Like I said, Im using the Rockford Fosgate Amp kit... but I can get a deal on the good Monster Cable stuff... such as these. Interconnects

Factory ground for the audio system is probably under the dash, usually at a metal support or attached directly to the metal body. The Ford factory wiring schematics would give you grounding locations. You may be able to find the CD manual on Ebay.

If you have all the amps and head unit grounded at the same point, then you eliminate the "ground loop".

The next best thing would be to ground both amps to the body as close to the amps as practical. Use large wire. If you still have the ground loop noise, then run a large wire from the amp ground to the head unit ground.

So I either need to ground the amps behind the head unit with a really long ground wire, or ground the amps as close as possible, with a connecting wire between the head unit ground and the amp ground? Sounds hard. heh. BTW, wouldnt it be easier to run the head unit ground to the amps instead? I know nothing about this stuff, buy Im guessing the head unit ground is smaller wire.

Im going to check where the amps are grounded tomorrow. Hopefully there is a ground point near the trunk area.

BTW, wouldnt it be easier to run the head unit ground to the amps instead? I know nothing about this stuff, buy Im guessing the head unit ground is smaller wire.

I suggest using large wire because you want the least resistance possible. Ideally, you would have all of them grounded at the same point with an infinitely short wire(s) connecting them.

It makes no difference to me whether you want to run the wire from the front back to the amps or from the amps up to the front. ;)

Maybe there is a factory ground on the backside of the hatch/trunk.

In my Toyota Paseo, there is one right next to the trunk's latch.

Click on this link and scroll down to the alternator whine part.
Dead Link Removed

Awesome link. Im just waiting for the wife to come home so I can start pokin around. In the event the RCA's are picking up noise at the headunit, is there anything I can do? Just try better RCA's?

Update: So I had about 45min of light after the woman go home... and after looking at the install, its not perfect but not bad. I noticed the power and ground wires crossed the RCA's going to my 4-channel amp. So I removed the RCA, and ran them away and in front of the amps (ugly as hell) but further and no longer touching the power and ground wires. The whine went away in the front speakers and decreased in the rear. At volume, you cannot hear the whine at all, but down low, its very annoying. Still an improvement though. I guess now Im confused as to why I have a whine on my rears and not my fronts. I suppose the 6 inch spread between the two connections on the amp could be making the difference... how far is far enough from the power/ground wires?

BTW, the power wire appears to be running with the speaker wire. Is this bad as well? Or does that just apply to the RCA's?

Anyways.... sorry for the wall of questions. But at least there is progress.